Choose timezone
Your profile timezone:
ALARA review for the replacement of the PSB dump (meeting 2)
→
Europe/Zurich
865/1-D17 (CERN)
ALARA review for the replacement of the PSB dump (18 Jul 2012)
Attendees: C. Bertone, T. Wijnands, A-P. Bernardes, O. Aberle, F. Loprete, R. Froeschl, J. Hansen, V. Raginel, A. Perillo-Marcone, V. Venturi, A. Sarrió.
Absents: D. Hay, N. Gilbert, Y. Bernard, J-M. Lacroix, Y. Algoet, N. Roget, G. Mason, K. Hanke, B. Mikulec.
INTRODUCTION:
A. Sarrió introduced the members of STI who are working on the design of the new PSB dump and on the replacement procedure.
All presentations, material and information about these meetings are available now in INDICO:
Projects > LHC Injectors Upgrade (LIU) > LIU-PSB > PSB dump: ALARA procedure meeting
https://indico.cern.ch/categoryDisplay.py?categId=4284
RADIOLOGICAL SITUATION OF THE CURRENT PSB DUMP:
R. Froeschl presented values of measurements taken in the area after ~1-2 day cool-down: a) dose rate profile in the beam pipe, b) dose rate at the most external concrete block, c) dose rate at the bottom rail (upstream end) and d) in contact with the beam pipe. He also estimated (FLUKA simulations) dose rates at the dump core and at the two furthest concrete blocks in the cavity.
An in-situ gamma spectrometry shows that Mn-54 (312 day half-life) and Co-60 (5.27 year half-life) are the dominant isotopes in the dump core.
Regarding the transport and storage of activated waste, some typical shielding materials were proposed as a reference, and their associated thicknesses.
According to the simulations, a cooling time of approximately 6 months is recommended. After that time, the reduction of radioactivity becomes less significant.
TRANSPORT AND STORAGE OF RADIOACTIVE WASTE:
The radioactive waste (beam pipe, dump core and concrete blocks) will be stored in ISR. After some time it can be brought to PSI (to be verified).
The yellow column (supporting the BTY-QFO108 magnet) will also become radioactive waste. Therefore, it will be brought to ISR. There are no current measurements of its dose rate.
T. Wijnands explained that the objects extracted from the radioactive area belong to their respective owners (STI) until they are brought and declared at ISR. Only then, they belong to RP.
Ask N. Gilbert or D. Hay where to store the elements from the beam line that will have been temporarily dismantled (Action for A. Sarrió).
O. Aberle asked if it is possible to use a shielding container which is bigger than what is actually needed, in order to reduce the dose rate outside by increasing the distance to the source. In that case, what are the limitations in terms of storage volume? R. Froeschl will ask Yvon Algoet (RP-Radioactive Waste).
There has to be a compromise between the measures taken in order to shield and transport radioactive waste and the dose received by the workers executing the shielding and transport tasks.
There are no explicit limitations in dose rate when transporting radioactive objects within the CERN site (C. Bertone).
WORK AND DOSE PLANNING (WDP): REPLACEMENT OF THE PSB DUMP:
A. Sarrió presented the main operations and tasks to be performed during the replacement works of the PSB dump: ‘Work-Dose-Planning_PSB_dump.xlsx’ available in INDICO.
The WDP file needs to be filled by all users responsible for a specific task. Share point can be a good solution for sharing this information between all parts.
The table below lists the names of the persons responsible for specific areas/operations:
Action: please provide for each group the name of the contact person.
The file must detail each single step of the operation (e.g. attach hook, screw/unscrew...), with an associated dose received by the worker.
The operations need to be prepared following the ALARA principle, in such a way that the workers receive the lowest possible dose. This means that the tasks will be optimised, the workers will be trained beforehand and the dose received will be monitored every day.
Since the dose rate at the beam pipe is very high and workers might need to get in contact with it, it was proposed the use of ring dosimeters. Even though, this is a passive measure, it would still be useful to know afterwards the actual dose the operators received on their hands.
Any possible risk of failure needs to be accounted for and, consequently, the best procedure needs to be chosen and detailed in the WDP. Only one WDP has to be prepared. In case the strategy goes wrong while being executed, the work is stopped and the new plan of execution will be discussed out of the radioactive area.
There was a discussion around the question on whether we need to prepare different tooling for the different scenarios, in case the execution plan fails. In general, it was agreed that given the complication and cost of the additional tooling and, considering that it may never be used, it would be best to manufacture the tools as required. Nevertheless, if the tooling is not very complicated or costly, it may be worth manufacturing them beforehand.
A risk analysis should be performed together with the WDP (Action for A. Sarrió, A. Perillo-Marcone).
It was recommended to mark the floor in order to delimit the most dangerous areas (e.g. at the exit of the dump cavity).
Panels/signs should be placed to clearly display the hot spots/sources.
An area with minimal exposure to irradiation should be defined so that people can spend longer time to discuss specifics of the current operations, prepare parts, etc.
A work supervisor (from EN-STI-TCD team) must be appointed. Besides, RP will be present at all times.
After removing the old dump, the end of the cavity (concrete) will probably be very active. This must be taken into account for the planning of the dismantling operations as well as for the installation of the new dump.
Study and design a moveable screen that could be used for the dismantling/installation operations and that can stay permanently in the area. There is currently a 1 cm lead screen, but this is probably insufficient. Several centimetres would be required (EN-STI-TCD).
Attendees: C. Bertone, T. Wijnands, A-P. Bernardes, O. Aberle, F. Loprete, R. Froeschl, J. Hansen, V. Raginel, A. Perillo-Marcone, V. Venturi, A. Sarrió.
Absents: D. Hay, N. Gilbert, Y. Bernard, J-M. Lacroix, Y. Algoet, N. Roget, G. Mason, K. Hanke, B. Mikulec.
INTRODUCTION:
A. Sarrió introduced the members of STI who are working on the design of the new PSB dump and on the replacement procedure.
All presentations, material and information about these meetings are available now in INDICO:
Projects > LHC Injectors Upgrade (LIU) > LIU-PSB > PSB dump: ALARA procedure meeting
https://indico.cern.ch/categoryDisplay.py?categId=4284
RADIOLOGICAL SITUATION OF THE CURRENT PSB DUMP:
R. Froeschl presented values of measurements taken in the area after ~1-2 day cool-down: a) dose rate profile in the beam pipe, b) dose rate at the most external concrete block, c) dose rate at the bottom rail (upstream end) and d) in contact with the beam pipe. He also estimated (FLUKA simulations) dose rates at the dump core and at the two furthest concrete blocks in the cavity.
An in-situ gamma spectrometry shows that Mn-54 (312 day half-life) and Co-60 (5.27 year half-life) are the dominant isotopes in the dump core.
Regarding the transport and storage of activated waste, some typical shielding materials were proposed as a reference, and their associated thicknesses.
According to the simulations, a cooling time of approximately 6 months is recommended. After that time, the reduction of radioactivity becomes less significant.
TRANSPORT AND STORAGE OF RADIOACTIVE WASTE:
The radioactive waste (beam pipe, dump core and concrete blocks) will be stored in ISR. After some time it can be brought to PSI (to be verified).
The yellow column (supporting the BTY-QFO108 magnet) will also become radioactive waste. Therefore, it will be brought to ISR. There are no current measurements of its dose rate.
T. Wijnands explained that the objects extracted from the radioactive area belong to their respective owners (STI) until they are brought and declared at ISR. Only then, they belong to RP.
Ask N. Gilbert or D. Hay where to store the elements from the beam line that will have been temporarily dismantled (Action for A. Sarrió).
O. Aberle asked if it is possible to use a shielding container which is bigger than what is actually needed, in order to reduce the dose rate outside by increasing the distance to the source. In that case, what are the limitations in terms of storage volume? R. Froeschl will ask Yvon Algoet (RP-Radioactive Waste).
There has to be a compromise between the measures taken in order to shield and transport radioactive waste and the dose received by the workers executing the shielding and transport tasks.
There are no explicit limitations in dose rate when transporting radioactive objects within the CERN site (C. Bertone).
WORK AND DOSE PLANNING (WDP): REPLACEMENT OF THE PSB DUMP:
A. Sarrió presented the main operations and tasks to be performed during the replacement works of the PSB dump: ‘Work-Dose-Planning_PSB_dump.xlsx’ available in INDICO.
The WDP file needs to be filled by all users responsible for a specific task. Share point can be a good solution for sharing this information between all parts.
The table below lists the names of the persons responsible for specific areas/operations:
| Name | Group/Section | Contact Person |
| Beam Intercepting Devices | EN-STI-TCD | O. Aberle |
| Vacuum | TE-VSC | |
| Magnets | TE-MSC | A. Newborough |
| Beam Instrumentation | BE-BI | |
| Survey | BE-ABP | |
| Transport and Handling | EN-HE | |
| Radioprotection | DGS-RP | R. Froeschl |
Action: please provide for each group the name of the contact person.
The file must detail each single step of the operation (e.g. attach hook, screw/unscrew...), with an associated dose received by the worker.
The operations need to be prepared following the ALARA principle, in such a way that the workers receive the lowest possible dose. This means that the tasks will be optimised, the workers will be trained beforehand and the dose received will be monitored every day.
Since the dose rate at the beam pipe is very high and workers might need to get in contact with it, it was proposed the use of ring dosimeters. Even though, this is a passive measure, it would still be useful to know afterwards the actual dose the operators received on their hands.
Any possible risk of failure needs to be accounted for and, consequently, the best procedure needs to be chosen and detailed in the WDP. Only one WDP has to be prepared. In case the strategy goes wrong while being executed, the work is stopped and the new plan of execution will be discussed out of the radioactive area.
There was a discussion around the question on whether we need to prepare different tooling for the different scenarios, in case the execution plan fails. In general, it was agreed that given the complication and cost of the additional tooling and, considering that it may never be used, it would be best to manufacture the tools as required. Nevertheless, if the tooling is not very complicated or costly, it may be worth manufacturing them beforehand.
A risk analysis should be performed together with the WDP (Action for A. Sarrió, A. Perillo-Marcone).
It was recommended to mark the floor in order to delimit the most dangerous areas (e.g. at the exit of the dump cavity).
Panels/signs should be placed to clearly display the hot spots/sources.
An area with minimal exposure to irradiation should be defined so that people can spend longer time to discuss specifics of the current operations, prepare parts, etc.
A work supervisor (from EN-STI-TCD team) must be appointed. Besides, RP will be present at all times.
After removing the old dump, the end of the cavity (concrete) will probably be very active. This must be taken into account for the planning of the dismantling operations as well as for the installation of the new dump.
Study and design a moveable screen that could be used for the dismantling/installation operations and that can stay permanently in the area. There is currently a 1 cm lead screen, but this is probably insufficient. Several centimetres would be required (EN-STI-TCD).
Next meeting, Wednesday 01/08/2012 – 10:30
There are minutes attached to this event.
Show them.
